§ II. On Consanguinity Insofar as It Is an Impediment of Marriage

I. The reasons for the established impediment are:

1. Reverence owed to blood-relatives. "Naturally a man owes a certain honor to parents, and consequently to those blood-relatives who draw their origin from the same parents from nearby... But it is manifest according to the things said above (q. 142, art. 4, and q. 151, art. 4) that in venereal acts there especially consists a certain baseness contrary to honor; whence men are ashamed concerning these things; and therefore it is unfitting that such venereal commingling should take place between such persons mutually" (St. Thomas, II-II, q. 154, a. 9).

2. The danger of lust to be forestalled. "Persons joined by blood must live together mutually; whence if men were not kept away from venereal commingling, too much opportunity of venereal commingling would be given to human beings, and thus the souls of human beings would be made too soft by lust" (St. Thomas, loc. cit.).

3. Friendship to be promoted. "For while a man takes a wife from outside, all the blood-relatives of the wife are joined to him by a certain special friendship, as if they were his own blood-relatives" (St. Thomas, loc. cit.).

4. Physical harms to be averted from offspring. Now some judge that consanguinity by itself alone produces harmful effects;¹ others deny this,² but concede that morbid qualities, which are found in families after the manner of a certain inheritance, are transmitted more easily and in a more intense degree through marriages between blood-relatives.³

¹ According to Dr. Rillet the effects of marriages of this sort are: sterility, abortion, monstrosity, epilepsy, imbecility, deaf-mutism, paralysis, etc. According to Dr. Boudin, in the city of Berlin, out of 10,000 Catholics there are found 3 deaf-mutes, out of the same number of Protestants 6, out of the same number of Jews 27. But among the latter blood-relatives are more joined in marriage, and Protestants more than Catholics, as all know (Eschbach, op. cit., p. 100; cf. Garnier, Le Mariage, p. 81; Devey, Des dangers des mariages consanguins; De Katholiek, 1884, p. 30, 173 sq.).

² So Dr. Surbled, who for the sake of argument relates these things: "The very precise observations collected on the island of Batz, isolated off Roscoff in Brittany, whose inhabitants, almost all relatives, truly form only one same family under the same bell-tower, demonstrate without reply that consanguineous unions give a strong, robust race, remarkably fruitful and endowed with longevity" (La morale dans ses rapports avec la medecine de l'hygiene, vol. I, chap. XVI).

³ Dr. Garnier: "Consanguinity must not... be confused with heredity or the transmission of diseases, affections, and constitutional defects, apparent or hidden... This danger exists for all unions tainted by any hereditary defect, for parents transmit to their children, by generation, the morbid predispositions with which they are affected, as they do their qualities and their defects, their physical and moral resemblance. But notable differences are observed in this regard in the results. In unions between unrelated persons, the reaction of contrary, opposed elements tends to neutralize and annihilate morbid germs; all great physicians have observed this, in effect, that chronic, hereditary affections, the deformities of a family, are extinguished and disappear in successive generations through well-made crossings." (Le Mariage, article "Mariages consanguins"). Dr. Surbled: "Performed between diathetic or degenerate persons, a consanguineous union is indubitably pernicious, deplorable, and can give only bad fruits; it unites weakened, sick, deviated constitutions... The grave diseases of ancestors, constitutional diatheses, as is known, have only too manifest a tendency to be transmitted in families. Now morbid consanguinity comes to strengthen this tendency and to accumulate elements of destruction in the generations which succeed one another" (loc. cit.).

II. The existence and scope of the impediment are established by these things:

1. In the direct line of consanguinity, marriage is invalid between all ascendants and descendants, both legitimate and natural (canon 1076, § 1). With regard to natural law, consanguinity certainly diriments marriage in the first degree of the direct line, and more probably in every degree. For marriage, which introduces a certain equality, is opposed to the relation of superiority and inferiority which exists between ascendants and descendants.

2. In the collateral line marriage is invalid up to the third degree inclusive (canon 1076, § 2).

With regard to natural law, consanguinity beyond the first degree does not diriment marriage.¹ Concerning the first degree itself, brother and sister, there is dispute. Several judge that such marriages are invalid, apart from the necessity of propagating the human race through the sons and daughters of Adam.² But they judge thus both because such marriages obstruct the primary end of marriage, since depraved offspring are accustomed to arise from them; and because admitted validity would give occasion for lust among persons living in the same house. Others admit the contrary, or at least call the matter into doubt, and respond that the integrity of offspring pertains only accidentally to the good of the species, to which marriage is ordered; and that the other reason does not seem so urgent that from it one may conclude to defect of validity.

As to positive law, there are those who judge that marriage between brother and sister is diriment by divine positive law. Others, however, rather deny this, because the Mosaic law has been abrogated, and the evangelical law says nothing concerning it.

Corollary. Marriage between infidels who are blood-relatives, whether in the first degree of the collateral line or in a further degree than the first degree of the direct line, is doubtfully valid. Hence if each, or one or the other, is converted to the faith, the Holy See must be approached.

3. The impediment of consanguinity was restricted by Leo XIII³ for Indians and Negroes⁴ in Latin America and in the Philippine Islands to the second degree of the collateral line. From the declaration of August 16, 1898, this also holds for all the Antilles and the other islands of the Caribbean Sea. We judge that, from the intention of the Legislator, the aforesaid disposition is governed by the law of privilege rather than by the law of a particular law, and therefore, although it is contrary to the general law, it persists.

III. Multiplication of the impediment. Before the current Code, the impediment was multiplied as often as consanguinity itself; but now the matrimonial impediment is multiplied only as often as the common stock is multiplied, or there are as many impediments as there are common stocks (canon 1076, § 2).

IV. Dispensation. The Church cannot dispense in the first degree of the direct line, since it constitutes an impediment of natural law. It is doubtful whether she can dispense in the other degrees of the direct line and in the first degree of the collateral line. In practice, she never dispenses in the aforesaid degrees. Hence canon 1076, § 3: "Marriage is never to be permitted if there is any doubt whether the parties are consanguineous in some degree of the direct line or in the first degree of the collateral line." From this it follows: 1° it can never be permitted to anyone, for example Peter, to marry either a person with whose mother he had copula at such a time before the daughter's birth that every danger of marrying his own daughter is not excluded; or a person with whose mother his father, that is, Peter's father, had copula at such a time before the daughter's birth that every danger of marrying his own sister is not excluded.⁵ 2° A Bishop or priest who can dispense in ecclesiastical impediments in danger of death or if all things are ready for nuptials cannot dispense from these impediments. In the other degrees of the collateral line the Church dispenses if a proportionately grave cause is present.

¹ Chapter 8, de divortiis.

² In this case there is not a dispensation in the law of nature, because due order requires that the good of an inferior order yield to the good of a superior order.

³ Constitution Trans oceanum, April 18, 1897.

⁴ Who come under the name of Indians and Negroes is taught by the Sacred Congregation for Extraordinary Ecclesiastical Affairs, May 24, 1898: "Under the name of Indians and Negroes, besides the Indians and Negroes themselves, are also included those who were begotten from an Indian or Negro man and a European woman, or a woman of European blood, and likewise those who were begotten from a European man and an Indian or Negro woman, and therefore are called Mixed, Mestizos, or Mulattoes, and have an absolute half of European blood. But those are not included who draw origin from Indians or Negroes only through a great-grandfather or grandmother, and who are called Quarterones, as having only a fourth part of Indian or Negro blood; and much less those who draw origin from Indians or Negroes only through a great-great-grandfather or great-great-grandmother and are commonly called Puchueles or Pucueles. Moreover, by the name of Indians and Negroes are also understood Africans, Asians, and Oceanians, provided they are not of European blood and are staying in Latin America, although they were not born there."

⁵ Pontifical Commission, June 2-3, 1918, ad 5 (A.A.S. 1918, p. 346).